Phantoms mimicking the viscoelastic behavior of healthy and fibrotic livers with Magnetic Resonance Elastography technique

The purpose was to develop phantoms mimicking the viscoelastic properties of healthy and fibrotic livers. Three plastic phantoms composed of different concentrations of plastisol (from 40% to 60%) were characterized at 60 Hz using Magnetic Resonance Elastography (MRE) tests. The Fibroscan (EchoSens) exam was used as the reference technique to identify the level of fibrosis (F). In parallel, the functional behavior (elasticity and viscosity) of healthy (F0) (N = 10) and fibrotic (minor (F1-F2): N = 20 and major F3-F4: N = 10) livers were determined with MRE. The same MRE protocol (driver, frequency, MR sequence) was used for in vivo and in vitro experiments. MRE post-processing was realized with two methods allowing for the local measurement of the mechanical properties (shear modulus: μ) and the global analysis of the viscoelastic behavior through cartographies of storage (G´) and loss (G") modulus. The results showed an increase of the viscoelastic (G´, G") values as a function of the plastic concentration and as a function of the fibrosis level. The phantoms made of 40 %, 50 % and 60 % showed similar elastic properties of healthy (F0), minor (F1-F2) and major (F3-F4) liver fibrosis, respectively. This study has demonstrated that the developed phantoms could mimic the functional properties of healthy and fibrotic livers.